The long range goal of this research is to develop models of the process whereby a speaker encodes a discrete linguistic representation of an utterance into patterns of movement of the articulatory structures and then into patterns of sound. Progress toward the development of these models makes it possible to contribute toward a second more practical goal. This second goal is to devise procedures for aiding with the assessment of deviations from normal functioning of the speech generation process through measurements of the acoustic pattern that results from this disordered speech production. The models can then be used to infer the movements of the articulators from the acoustic measurements. The development of models of the normal speech production process will be advanced through a combination of theoretical analysis of sound generation and filtering in the vocal tract, and collection of acoustic data from a variety of utterances of normal speakers. The acoustic data will be augmented in some cases by physiological data and by perceptual studies with synthetic speech. The acoustic data will be used for two purposes. One is to provide support for the acoustic theory that attempts to predict sound patterns when articulatory movements are known or can be estimated. The second is to provide some basic information about the ways in which speakers manipulate and coordinate different articulators when particular sequence of linguistic units (syllables, segment, features) are encoded into sound. In the proposed research, emphasis will be placed on the production of liquids, glides, nasal consonants, nasal vowels, and fricative and stop consonants. Acoustic data will be used to infer the movement of the articulators for segment sequences consisting of certain consonant clusters within and across syllable boundaries and to examine laryngeal adjustments in sentences in syllables having different degrees of prominence or reduction. The development of procedures for using acoustic measurements to assist in evaluating speech disorders will involve collaboration with clinicians. A limited number of disorders will be studied, and samples of speech from individuals with these disorders will be analyzed exhaustively. The result of the analysis will be interpreted to infer deviations in the control of movements of the different articulatory structures. The gains to be achieved by augmenting conventional assessment methods with acoustic analysis will be addressed.